Quick Facts
- Sample: Blood (5 timed specimens via venipuncture)
- Fasting: 8+ hours required
- Turn-around: 4-5 business days. May take longer based on weather, holiday, or lab delays.
Benefits
- Precise diagnosis through five timed blood samples for accurate lactose digestion assessment
- Fast results with same-day turnaround to quickly guide dietary decisions
- No referral needed - order directly and get physician-reviewed results confidentially
- Avoid guesswork - distinguish lactose intolerance from other digestive issues
- Prevent complications - early detection helps avoid malnutrition and bone health issues
- Cost-effective alternative to specialist visits for initial lactose intolerance screening
Who Is This Test For?
- People experiencing bloating, gas, diarrhea, or cramps after dairy consumption
- Individuals with family history of lactose intolerance seeking confirmation
- Those with suspected malabsorption disorders or digestive health concerns
- Adults wanting to optimize their diet based on lactose tolerance levels
- Patients with conditions like Crohn's disease or celiac disease affecting lactose digestion
- Anyone seeking to understand recurring digestive symptoms linked to dairy products
How It Works – Just 3 Steps
- Fast and arrive - Fast for 8+ hours, then visit the lab for your baseline blood draw
- Drink and wait - Consume the lactose solution and have blood drawn at 30, 60, 90, and 120 minutes
- Get results - Receive secure results within 4-5 days in secure online account
FAQ
What does this test measure? Blood glucose levels at five time points after lactose consumption to assess lactose digestion efficiency.
How is this different from a breath test? Blood testing directly measures glucose absorption, while breath tests measure hydrogen gas from undigested lactose.
Can I take my regular medications? Consult your physician about medications affecting carbohydrate metabolism before testing.
Will this test detect milk allergies? No, this test only detects lactase deficiency, not immune-mediated milk allergies requiring separate testing.
How long does the test take? Approximately 2.5 hours total, including the 2-hour monitoring period after lactose consumption.
Is this test suitable for children? Yes, though pediatric dosing and alternative tests like stool acidity may be considered for young children.
More Details
What is the purpose of this test?
The Lactose Tolerance Blood Test measures your body's ability to digest lactose by tracking blood glucose changes over two hours after consuming a standardized lactose solution. This test evaluates lactase enzyme activity in your small intestine, which breaks down lactose into glucose and galactose for absorption (Mayo Clinic 2024). When lactase is deficient, lactose remains undigested, resulting in minimal blood glucose elevation and confirming lactose intolerance.
Who would benefit from this test?
This test is ideal for individuals experiencing gastrointestinal symptoms like bloating, diarrhea, gas, or abdominal pain after consuming dairy products (CDC 2023). It's particularly valuable for people with family history of lactose intolerance, those with malabsorption disorders, or individuals with conditions affecting intestinal health like Crohn's disease or celiac disease. The test also helps distinguish lactose intolerance from other digestive conditions, enabling targeted dietary management.
When should I order a Lactose Tolerance Blood Test - 5 Specimen?
Order this test when experiencing recurring digestive symptoms consistently linked to dairy consumption. Consider testing if you have persistent bloating, cramping, diarrhea, or gas within hours of eating dairy products. The test is also recommended for individuals with family history of lactose intolerance or those with conditions affecting small bowel function (Johns Hopkins Medicine 2024).
How do I interpret the results?
Glucose rise ≥30 mg/dL
- What it means: Normal lactose tolerance
- Typical action: Continue regular dairy consumption
Glucose rise 20–29 mg/dL
- What it means: Intermediate/mild intolerance
- Typical action: Reduce dairy; consider lactase supplements
Glucose rise <20 mg/dL
- What it means: Lactose intolerance
- Typical action: Avoid lactose; use lactose-free alternatives
Approximately 65% of adults worldwide have some degree of lactose malabsorption, with significant variation by ethnicity (NIH 2023).
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
Pre-test preparation
Fast for at least 8 hours before your appointment, consuming only water. Avoid chewing gum, smoking, and vigorous exercise on test day as these can affect glucose levels. Consult your physician about temporarily discontinuing medications that may interfere with carbohydrate metabolism. Wear comfortable clothing with easy arm access for multiple blood draws during the 2-hour testing period.
How often should I get tested?
- Initial diagnosis – Once, unless symptoms change
- Following intestinal surgery – 3–6 months post-procedure
- Managing Crohn's/celiac disease – Annually or per physician guidance
- Symptom changes – As needed for reassessment
Why early detection matters
Early detection of lactose intolerance prevents unnecessary dietary restrictions and reduces risk of malnutrition or calcium deficiency from avoiding all dairy products (American Gastroenterological Association 2023). Proper diagnosis enables targeted dietary management using lactase supplements and lactose-free products, maintaining nutritional adequacy while eliminating digestive discomfort. Early identification also prevents misdiagnosis of other gastrointestinal conditions.
Related tests you may consider
Bacterial Overgrowth of the Small Intestine (SIBO) Breath Test 3-Hours - Genova Test Kit - as a non-invasive alternative that measures hydrogen and methane gas from undigested lactose fermentation.
Glucose Tolerance Test - helps rule out diabetes or glucose metabolism disorders that could affect interpretation.
Comprehensive Metabolic Panel - to evaluate overall gastrointestinal function and rule out other malabsorption conditions.
